The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in the present disclosure and are not admitted to be prior art by the inclusion in this section.
Currently, wireless networks do not offer comprehensive coverage of all geographic locations. That is, wireless network coverage offered by a first service provider may be absent in one location while a second service provider may feature wireless network coverage in that same location, and vice versa for a different location. While a user equipment (“UE”) may have the capability to operate on wireless networks provided by both the first and second service providers, the UE may only subscribe to the first service provider. Therefore, absent a roaming agreement between the two service providers, the UE is forbidden from receiving mobile-terminated conversational calls through the wireless network of the second service provider. In areas where only the second service provider offers wireless coverage, the UE may camp on the forbidden network of the second service provider, but only with limited service. Because the UE is operating with limited service on the forbidden network, the UE will be unable to receive mobile-terminated conversational calls.
The inability to establish a mobile-terminated conversational call with a UE that is camped on a forbidden network is especially problematic when emergency services need to reach the UE. The UE may still be able to receive paging messages that are transmitted within a cell, and so may be alerted to generic paging messages used for Earthquake and Tsunami Warning System (“ETWS”) messages. However, the UE may be unable to receive individual communications from emergency services.